*2.5. Barrier Properties*

The water vapor permeability (WVP) and moisture content of hydrogel-based films made of pectin and collagen and loaded with different concentrations of MOEO were assessed. The results indicated that the control film sample (B) without the addition of MOEO showed higher values for WVP as compared to the film samples loaded with oil (Table 2). The WVP of the film samples decreased from 0.676 to 0.327 (g mm)/(m<sup>2</sup> h kPa) with increasing concentrations of MOEO. This behavior of the films could be due to the hydrophobicity of the MOEO causing the inhibition of water permeability, since the Tween 80 has a hydrophilic character. The water WVP of the film could be affected by the hydrophilic–lipophilic ratio of the film matrix, as water diffuses through the hydrophilic section of the matrix [23]. In addition, the reduced WVP of the films could be ascribed to the crosslinking between the polymer chains and reduced chain mobility with the addition of MOEO and Tween 80, resulting from the filling of empty spaces in the film matrix [24]. Similar findings were reported by Almasi et al. [23], wherein the pectin-based hydrogel films resulted in to decrease in the permeability of water vapors when loaded with marjoram essential oil nanoemulsions.

Assessment of the moisture content is a crucial parameter because it affects the mechanical, barrier, and sensory characteristics of the films. The film samples that were loaded with MOEO exhibited a lower level of moisture content in comparison to the control film, as indicated in Table 2. The moisture content decreased from 29.92 to 25.16% with increasing

concentrations of the oil in the film samples. The findings of the present investigation are consistent with those obtained by Nisar et al. [25], who found that the incorporation of clove bud essential oil into edible films based on citrus pectin resulted in a decrease in the amount of water present in the films.
